Wave propagation and tunneling through periodic structures

The phenomenon of tunneling manifests itself in nearly every field of physics. The ability to distinguish a wave tunneling through a barrier from one propagating is important for a number of applications. Here we explore the properties of the wave traveling through the band gap created by a lattice, either as a consequence of tunneling through the barrier or due to the presence of a pass band inside the gap. To observe the pass band for studying tunneling and propagating waves simultaneously, a localized lattice defect was introduced. The differences between the two phenomena are highlighted via waves' dispersion characteristics

Bento Box—Modular/Recoverable Stratospheric Balloon Capabilities to Support Distributed Maritime Operations

NPS NRP Executive SummaryChief of Naval Operations, ADM Gilday, and Commandant of the Marine Corps, Gen Berger, directed modernization efforts across the Naval Services. The concept of Naval Operational Architecture (NOA) enables the development of additional beyond-line-of-sight (BLOS) targeting and fires delivered from widely distributed points within and outside a near-peer's weapons engagement zones (WEZ). Research into proliferated low-earth orbiting communications satellites (pLEO) reveal an intersection with the Joint All Domain Command and Control (JADC2) priority and the Navy and Marine components leveraging efforts such as Task Force Overmatch (DEVSECOPS). There is an immediate need to develop requirements and analyze alternate architectures for delivering BLOS precision fires in future contested environments in the context of Great Power Competition. Faculty experience with space mission architecture design will be leveraged to advise students in achieving the following objectives: 1) Research and develop operational, functional objective and threshold requirements for a proliferated LEO systems within the JADC2 framework to enable BLOS precision fires. 2) Analyze alternative architectures for the requirements which enable BLOS precision fires in a contested environment. A phased approach will be used to meet the research objectives. First, a capabilities or system requirements-like document will be generated to include validation criteria and in-phase lessons learned. Second, standard aerospace modeling/simulation techniques will be used to define the mission and architecture requirements and analyze the alternatives for architectures enabling BLOS precision fires through a contested environment to include in-phase lessons learned. Third, individual student thesis research will occur to completion/graduation of the students and any final closing actions through the remainder of the project period.Naval Special Warfare Command (NAVSPECWARCOM)N9 - Warfare SystemsThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Bento Box—Modular/Recoverable Stratospheric Balloon Capabilities to Support Distributed Maritime Operations

NPS NRP Project PosterChief of Naval Operations, ADM Gilday, and Commandant of the Marine Corps, Gen Berger, directed modernization efforts across the Naval Services. The concept of Naval Operational Architecture (NOA) enables the development of additional beyond-line-of-sight (BLOS) targeting and fires delivered from widely distributed points within and outside a near-peer's weapons engagement zones (WEZ). Research into proliferated low-earth orbiting communications satellites (pLEO) reveal an intersection with the Joint All Domain Command and Control (JADC2) priority and the Navy and Marine components leveraging efforts such as Task Force Overmatch (DEVSECOPS). There is an immediate need to develop requirements and analyze alternate architectures for delivering BLOS precision fires in future contested environments in the context of Great Power Competition. Faculty experience with space mission architecture design will be leveraged to advise students in achieving the following objectives: 1) Research and develop operational, functional objective and threshold requirements for a proliferated LEO systems within the JADC2 framework to enable BLOS precision fires. 2) Analyze alternative architectures for the requirements which enable BLOS precision fires in a contested environment. A phased approach will be used to meet the research objectives. First, a capabilities or system requirements-like document will be generated to include validation criteria and in-phase lessons learned. Second, standard aerospace modeling/simulation techniques will be used to define the mission and architecture requirements and analyze the alternatives for architectures enabling BLOS precision fires through a contested environment to include in-phase lessons learned. Third, individual student thesis research will occur to completion/graduation of the students and any final closing actions through the remainder of the project period.Naval Special Warfare Command (NAVSPECWARCOM)N9 - Warfare SystemsThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

A cusp electron gun for millimeter wave gyro-devices

A thermionic cusp electron gun has been designed, numerically optimized and experimentally measured and is presented. A 40 kV, 1.5 A annular axis-encircling electron beam has been simulated to generate a beam with low velocity and alpha spreads. The electron gun performance has been verified through experiments. Based on the measured results further improvement and optimization of the cusp gun for high frequency operation were carried out and the results will be presented

Proliferated LEO Architecture Enabling Beyond Line of Sight Fires (pLEO BLOS Fires)

NPS NRP Project PosterChief of Naval Operations, ADM Gilday, and Commandant of the Marine Corps, Gen Berger, directed modernization efforts across the Naval Services. The concept of Naval Operational Architecture (NOA) enables the development of additional beyond-line-of-sight (BLOS) targeting and fires delivered from widely distributed points within and outside a near-peer's weapons engagement zones (WEZ). Research into proliferated low-earth orbiting communications satellites (pLEO) reveal an intersection with the Joint All Domain Command and Control (JADC2) priority and the Navy and Marine components leveraging efforts such as Task Force Overmatch (DEVSECOPS). There is an immediate need to develop requirements and analyze alternate architectures for delivering BLOS precision fires in future contested environments in the context of Great Power Competition. Faculty experience with space mission architecture design will be leveraged to advise students in achieving the following objectives: 1) Research and develop operational, functional objective and threshold requirements for a proliferated LEO systems within the JADC2 framework to enable BLOS precision fires. 2) Analyze alternative architectures for the requirements which enable BLOS precision fires in a contested environment. A phased approach will be used to meet the research objectives. First, a capabilities or system requirements-like document will be generated to include validation criteria and in-phase lessons learned. Second, standard aerospace modeling/simulation techniques will be used to define the mission and architecture requirements and analyze the alternatives for architectures enabling BLOS precision fires through a contested environment to include in-phase lessons learned. Third, individual student thesis research will occur to completion/graduation of the students and any final closing actions through the remainder of the project period.Marine Corps Capabilities Development Directorate (CDD), DC CD&IHQMC Combat Development and Integration (CD&I)This research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Proliferated LEO Architecture Enabling Beyond Line of Sight Fires (pLEO BLOS Fires)

NPS NRP Executive SummaryChief of Naval Operations, ADM Gilday, and Commandant of the Marine Corps, Gen Berger, directed modernization efforts across the Naval Services. The concept of Naval Operational Architecture (NOA) enables the development of additional beyond-line-of-sight (BLOS) targeting and fires delivered from widely distributed points within and outside a near-peer's weapons engagement zones (WEZ). Research into proliferated low-earth orbiting communications satellites (pLEO) reveal an intersection with the Joint All Domain Command and Control (JADC2) priority and the Navy and Marine components leveraging efforts such as Task Force Overmatch (DEVSECOPS). There is an immediate need to develop requirements and analyze alternate architectures for delivering BLOS precision fires in future contested environments in the context of Great Power Competition. Faculty experience with space mission architecture design will be leveraged to advise students in achieving the following objectives: 1) Research and develop operational, functional objective and threshold requirements for a proliferated LEO systems within the JADC2 framework to enable BLOS precision fires. 2) Analyze alternative architectures for the requirements which enable BLOS precision fires in a contested environment. A phased approach will be used to meet the research objectives. First, a capabilities or system requirements-like document will be generated to include validation criteria and in-phase lessons learned. Second, standard aerospace modeling/simulation techniques will be used to define the mission and architecture requirements and analyze the alternatives for architectures enabling BLOS precision fires through a contested environment to include in-phase lessons learned. Third, individual student thesis research will occur to completion/graduation of the students and any final closing actions through the remainder of the project period.Marine Corps Capabilities Development Directorate (CDD), DC CD&IHQMC Combat Development and Integration (CD&I)This research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Broadband amplification of low-terahertz signals using axis-encircling electrons in a helically corrugated interaction region

Experimental results are presented of a broadband, high power, gyrotron traveling wave amplifier (gyro-TWA) operating in the (75–110)-GHz frequency band and based on a helically corrugated interaction region. The second harmonic cyclotron mode of a 55-keV, 1.5-A, axis-encircling electron beam is used to resonantly interact with a traveling TE21-like eigenwave achieving broadband amplification. The gyro-TWA demonstrates a 3-dB gain bandwidth of at least 5.5 GHz in the experimental measurement with 9 GHz predicted for a wideband drive source with a measured unsaturated output power of 3.4 kW and gain of 36–38 dB. The approach may allow a gyro-TWA to operate at 1 THz

Compact millimetre wave and terahertz radiation sources driven by pseudospark-generated electron beam

A pseudospark (PS) plasma sourced electron beam was both computationally and experimentally studied for generation of millimetre wave and terahertz radiation. The beam-wave interaction region is a sinusoidal rippled-wall slow wave structure of a backward wave oscillator (BWO) in G-band. An electron beam of ∼1 mm diameter carrying a current of up to 10 A with a sweeping voltage of 42 to 25 kV and pulse duration of 25 ns propagated through the interaction region in a plasma environment without the need for a guiding magnetic field, which resulted in broadband millimetre radiation generation over a frequency range of 186-202 GHz with a maximum power of 20 W

Numerical simulation of unconstrained cyclotron resonant maser emission

When a mainly rectilinear electron beam is subject to significant magnetic compression, conservation of magnetic moment results in the formation of a horseshoe shaped velocity distribution. It has been shown that such a distribution is unstable to cyclotron emission and may be responsible for the generation of Auroral Kilometric Radiation (AKR) an intense rf emission sourced at high altitudes in the terrestrial auroral magnetosphere. PiC code simulations have been undertaken to investigate the dynamics of the cyclotron emission process in the absence of cavity boundaries with particular consideration of the spatial growth rate, spectral output and rf conversion efficiency. Computations reveal that a well-defined cyclotron emission process occurs albeit with a low spatial growth rate compared to waveguide bounded simulations. The rf output is near perpendicular to the electron beam with a slight backward-wave character reflected in the spectral output with a well defined peak at 2.68GHz, just below the relativistic electron cyclotron frequency. The corresponding rf conversion efficiency of 1.1% is comparable to waveguide bounded simulations and consistent with the predictions of kinetic theory that suggest efficient, spectrally well defined radiation emission can be obtained from an electron horseshoe distribution in the absence of radiation boundaries.Publisher PD

Numerical simulation of astrophysical cyclotron-maser emission

Numerical simulations have been conducted at the University of Strathclyde to study the spatial growth rate and emission topology of the cyclotron maser instability responsible for auroral magnetospheric radio emission from stars and planets and intense non-thermal radio emission in other astrophysical contexts. The results have significant bearing on the radiation propagation characteristics and highly debated question of escape from the source region